Automatic backoff of a spectrum allocation server heartbeat

ABSTRACT

During operation, a radio node may provide, at a transmit time during a first time interval, a first instance of a keep-alive message to a computer. Then, the radio node may receive, at a receive time prior to a first instance of a transmit expire time, an instance of a keep-alive response from the computer, where the instance of the keep-alive response authorizes the radio node to transmit in a granted portion of the spectrum until a second instance of the transmit expire time has elapsed. Moreover, the radio node may determine, based at least in part on the receive time and the first instance of the transmit expire time, an updated transmit time. Next, the radio node may provide, at the updated transmit time, which is prior to the second instance of the transmit expire time, a second instance of the keep-alive message addressed to the computer.

BACKGROUND Field

The described embodiments relate to techniques for communicatinginformation among electronic devices. Notably, the described embodimentsrelate to techniques for dynamically adjusting a transmit time of aheartbeat request to a spectrum allocation server (SAS).

Related Art

While many electronic devices communicate with each other via largenetworks owned by a network operator, small-scale networks associatedwith entities (such as a company or an organization) are increasinglycommon. In principle, the small-scale network complements the serviceoffered by the network operator and can offer improved communicationperformance, such as in a particular venue or environment. In practice,the communication performance of small-scale networks (and largenetworks) is often constrained by resources, such as bandwidth in ashared communication channel.

In order to address these constraints, additional bands of frequenciesare being used by large networks and small-scale networks. For example,the shared-license-access band of frequencies near 3.5 GHz (notably, the150 MHz of bandwidth between 3.55 GHz and 3.7 GHz) is being used forgeneral-purpose communication. This shared-license-access band offrequencies is referred to as ‘Citizens Broadband Radio Service’ orCBRS.

In CBRS, a radio node (which is sometimes referred to as a ‘CitizensBand Service Device’ or CBSD) may provide a grant request to a SAS (acloud-based service that manages wireless communication in the CBRS) toreserve a portion of the spectrum or bandwidth in theshared-license-access band of frequencies for its use. For example, aradio node may request a grant to reserve a specific 5 MHz block ofspectrum from the SAS. If the requested portion of the spectrum isavailable, the SAS may provide a grant response to the radio node withapproval of a grant for the requested portion of the spectrum. Then, theradio node may provide a heartbeat request to the SAS to requestauthorization to transmit in the granted portion of the spectrum. Whenthe radio node receives a subsequent heartbeat response from the SAS,the radio node is authorized to transmit in the granted portion of thespectrum.

However, the authorization to transmit from the SAS is temporary andneeds to be periodically renewed by the radio node (e.g., every 4 min.).If the authorization to transmit is not renewed in time, then the radionode may no longer be able to transmit in the granted portion of thespectrum. Instead, the radio node may need to repeat the grant-requestand authorization process with the SAS, which can be time-consuming andcan result in degraded service while the granted portion of the spectrumis not available for use.

SUMMARY

A radio node that dynamically adjusts a transmit time of instances ofkeep-alive messages to a computer is described. This radio nodeincludes: a node or connector; and an interface circuit thatcommunicates with the computer. During operation, the interface circuitprovides, at a transmit time during a first time interval correspondingto a first instance of a transmit expire time, a first instance of akeep-alive message addressed to the computer, where a given instance ofthe keep-alive message requests authorization to transmit in a grantedportion of a spectrum. Then, the interface circuit receives, at areceive time prior to the first instance of a transmit expire time, aninstance of a keep-alive response associated with the computer, wherethe instance of the keep-alive response authorizes the radio node totransmit in the granted portion of the spectrum until a second instanceof the transmit expire time has elapsed. Moreover, the interface circuitdetermines, based at least in part on the receive time and the firstinstance of the transmit expire time, an updated transmit time, wherethe updated transmit time is temporally offset relative to a transmittime during a second time window corresponding to the second instance ofthe transmit expire time. Next, the interface circuit provides, at theupdated transmit time, which is prior to the second instance of thetransmit expire time, a second instance of the keep-alive messageaddressed to the computer.

Note that the computer may include a SAS. Moreover, the spectrum may beincluded in a CBRS.

Furthermore, the updated transmit time may be determined based at leastin part on a difference between the transmit expire time and the receivetime. Additionally, the updated transmit time may be determined based atleast in part on the transmit time.

In some embodiments, the updated transmit time may be determined basedat least in part on a number of instances of the keep-alive message thatwere provided until the keep-alive response was received. Alternativelyor additionally, the updated transmit time may be determined based atleast in part on a previous occurrence in which no instance of thekeep-alive response is received prior to a previous instance of thetransmit expire time.

Moreover, the updated transmit time may precede a start of the secondtime interval.

Furthermore, the given instance of the keep-alive message may include aheartbeat request, the keep-alive response may include a heartbeatresponse, and a given time interval may include a heartbeat interval.

Additionally, the communication with the computer may use wiredcommunication.

Note that the radio node may include: an Evolved Node B (eNodeB), aUniversal Mobile Telecommunications System (UMTS) NodeB and radionetwork controller (RNC), a New Radio (NR) gNB or gNodeB (whichcommunicates with a network with a cellular-telephone communicationprotocol that is other than Long Term Evolution), etc.

Another embodiment provides the computer.

Another embodiment provides a computer-readable storage medium withprogram instructions for use with the radio node. When executed by theradio node, the program instructions cause the radio node to perform atleast some of the aforementioned operations in one or more of thepreceding embodiments.

Another embodiment provides a method, which may be performed by theradio node. This method includes at least some of the aforementionedoperations in one or more of the preceding embodiments.

This Summary is provided for purposes of illustrating some exemplaryembodiments, so as to provide a basic understanding of some aspects ofthe subject matter described herein. Accordingly, it will be appreciatedthat the above-described features are examples and should not beconstrued to narrow the scope or spirit of the subject matter describedherein in any way. Other features, aspects, and advantages of thesubject matter described herein will become apparent from the followingDetailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram illustrating an example of communication amonga computer, radio nodes and electronic devices in a system in accordancewith an embodiment of the present disclosure.

FIG. 2 is a flow diagram illustrating an example of a method fordynamically adjusting a transmit time of an instance of a keep-alivemessage using a radio node in FIG. 1 in accordance with an embodiment ofthe present disclosure.

FIG. 3 is a drawing illustrating an example of communication among theelectronic devices in FIG. 1 in accordance with an embodiment of thepresent disclosure.

FIG. 4 is a drawing illustrating an example of a technique fordynamically adjusting a transmit time of a heartbeat request to a SAS inaccordance with an embodiment of the present disclosure.

FIG. 5 is a block diagram illustrating an example of an electronicdevice in accordance with an embodiment of the present disclosure.

Note that like reference numerals refer to corresponding partsthroughout the drawings. Moreover, multiple instances of the same partare designated by a common prefix separated from an instance number by adash.

DETAILED DESCRIPTION

A radio node that dynamically adjusts a transmit time of instances ofkeep-alive messages to a computer is described. During operation, theradio node may provide, at a transmit time during a first time intervalcorresponding to a first instance of a transmit expire time, a firstinstance of a keep-alive message to the computer, where a given instanceof the keep-alive message requests authorization to transmit in agranted portion of a spectrum. Then, the radio node may receive, at areceive time prior to the first instance of a transmit expire time, aninstance of a keep-alive response from the computer, where the instanceof the keep-alive response authorizes the radio node to transmit in thegranted portion of the spectrum until a second (subsequent) instance ofthe transmit expire time has elapsed. Moreover, the radio node maydetermine, based at least in part on the receive time and the firstinstance of the transmit expire time, an updated transmit time, wherethe updated transmit time is temporally offset relative to a transmittime during a second time window corresponding to the second instance ofthe transmit expire time. Next, the radio node may provide, at theupdated transmit time, which is prior to the second instance of thetransmit expire time, a second instance of the keep-alive messageaddressed to the computer.

By dynamically adjusting the transmit time of instances of thekeep-alive messages, this communication technique may ensure continuityof communication using the granted portion of the spectrum. For example,by adjusting the transmit time, the communication technique may ensurethat the keep-alive responses are received prior to the instances of thetransmit expire time, even when there are dynamic or time-varying delaysat the computer or in communication with the computer, and/or one ormore retries of keep-alive messages (e.g., because of dropped packets).Consequently, the updated transmit time may ensure that there issufficient temporal margin between an instance of the receive time andan instance of the transmit expire time. Therefore, the communicationtechnique may ensure that the granted portion of the spectrum remainsauthorized for use by the radio node across multiple instances of thetransmit expire time, which may eliminate the need for a subsequentgrant request for the portion of the spectrum. Thus, the communicationtechnique may reduce or eliminate time delays, and may ensure improvedcommunication and quality of service in a network that includes theradio node.

We now describe some embodiments of the communication technique. Acellular-telephone network may include base stations (and associatedcell towers) that implement so-called ‘macrocells.’ These macrocells mayfacilitate communication with hundreds of users (such as hundreds ofcellular telephones) over distances of kilometers. In general, thepositioning of the cell towers (and the antennas) is carefully designedand optimized to maximize the performance of the cellular-telephonenetwork (such as the throughput, the capacity, the block error rate,etc.) and to reduce crosstalk or interference between the signalstransmitted by different cell towers and/or different macrocells. Smallcells are generally radio access nodes providing lower power thanmacrocells and therefore providing smaller coverage areas thanmacrocells. It is common to subcategorize ‘small cells’ even further byascribing relative general ranges. For example, a ‘microcell’ might havea range of less than 2 kilometers, a “picocell” less than 200 meters,and a ‘femtocell’ on the order of 10 meters. These descriptions are forgeneral relative comparison purposes and should not be limiting on thescope of the disclosed embodiments of the communication technique.

However, there are often gaps in the coverage offered by macrocells.Consequently, some users operate local transceivers that provideshort-range communication in the cellular-telephone network. Theseso-called ‘femto cells’ provide short-range communication (e.g., up to10 m) for a few individuals.

In addition, larger organizations (such as those with 50-60 users, whichis a non-limiting numerical example) may operate local transceivers thatprovide communication in the cellular-telephone network over a range of100 m. This intermediate-range coverage in the cellular-telephonenetwork can be typically referred to as a ‘small cell’ as well.

One challenge for operators of cellular-telephone networks ismaintaining network performance and quality. For example, it may bedifficult to maintain the network performance and the quality of servicein high density, indoor or crowded environments. While the use of femtocells and/or small cells can mitigate this challenge, there are stilloften circumstances where the network performance and quality of acellular-telephone network is degraded. As noted previously, a radionode may need to periodically exchange heartbeat messages with a SAS inorder to renew a temporary authorization to use a granted portion of aspectrum (such as in the CBRS). If delays in communication with the SAS,delays in processing of a heartbeat request by the SAS and/or multipleheartbeat-request retires are needed (e.g., because of dropped packetsor frames), the authorization to transmit may not be renewed in time.When this occurs, a radio node may need to cease its radio-frequencytransmission and may change the grant state to suspended. Then, theradio node may need to repeat a grant-request and authorization processwith the SAS, which can be time-consuming and can result in degradedservice while the granted portion of the spectrum is not available.These challenges are addressed in the communication technique describedbelow.

In the discussion that follows, Long Term Evolution or LTE (from the 3rdGeneration Partnership Project of Sophia Antipolis, Valbonne, France) isused as an illustration of a data communication protocol in acellular-telephone network that is used during communication between oneor more radio nodes and an electronic device. Consequently, eNodeBs oreNBs are used as illustrative examples of the radio nodes. However, awide variety of communication techniques or protocols may be readilyused for the various embodiments. For example, an electronic device anda radio node may communicate frames or packets in accordance with awireless communication protocol, such as an Institute of Electrical andElectronics Engineers (IEEE) 802.11 standard (which is sometimesreferred to as ‘Wi-Fi,’ from the Wi-Fi Alliance of Austin, Tex.),Bluetooth (from the Bluetooth Special Interest Group of Kirkland,Wash.), a cellular-telephone or data network (such as using a thirdgeneration or 3G communication protocol, a fourth generation or 4Gcommunication protocol, e.g., LTE, LTE Advanced or LTE-A, a fifthgeneration or 5G communication protocol, or other present or futuredeveloped advanced cellular communication protocol) and/or another typeof wireless interface (such as communication protocol). Thus, the radionodes may include: an eNodeB, a UMTS NodeB and RNC, an NR gNB or gNodeB,etc.

Moreover, a radio node may communicate with other radio nodes and/orcomputers in a network using a wired communication protocol, such as anIEEE 802.3 standard (which is sometimes referred to as ‘Ethernet’)and/or another type of wired interface. In the discussion that follows,Ethernet is used as an illustrative example.

FIG. 1 presents a block diagram illustrating an example of communicationamong electronic devices according to some embodiments. Notably, radionodes 110 can communicate LTE data frames or packets using LTE with anelectronic device 112 (which is sometimes referred to as ‘userequipment’ or UE, such as a cellular telephone and, more generally, aportable electronic device). Again, while LTE is used as an example of acellular protocol, the embodiments herein are not so limited. Moreover,radio nodes 110 may also communicate (via wireless or wiredcommunication, such as Ethernet, in network 114) with each other andwith computer 124 (such as a SAS).

As described further below with reference to FIGS. 2-4, one or more ofradio nodes 110 may perform a communication technique by communicatingwith computer 124 via network 114. Using radio node 110-1 as an example,this radio node may provide a grant request to computer 124 to reserve aportion of a spectrum or bandwidth (such as a portion of the spectrum ina shared-license-access band of frequencies or another band offrequencies) for its use. For example, radio node 110-1 may request agrant to reserve 5, 10, 20, 40, 80, 100 or 150 MHz of spectrum in aparticular geographic region in the CBRS from computer 124. In response,computer 124 may provide a grant response to radio node 110-1 withapproval of a grant for the requested portion of the spectrum.

Then, radio node 110-1 may request from computer 124 authorization totransmit in the granted portion of the spectrum. For example, radio node110-1 may provide a first instance of a (periodic) keep-alive message(such as a heartbeat request) to computer 124 in order to requestauthorization to transmit in the granted portion of the spectrum.Notably, radio node 110-1 may provide the first instance of thekeep-alive message at a transmit time during a time interval (such as astart of a heartbeat interval or duration). When radio node 110-1receives, at a receive time prior to prior to a first instance of atransmit expire time, an instance of a keep-alive response from computer124, then radio node 110-1 may be authorized to transmit in the grantedportion of the spectrum until a subsequent instance of the transmitexpire time has elapsed.

However, if there are delays (e.g., in network 114 and/or computer 124),if retries are needed (such as because of dropped packets or frames), orboth, a given instance of the keep-alive response may not be received intime (i.e., before a given instance of a transmit expire time). Whenthis occurs, radio node 110-1 may not be allowed to transmit in thegranted portion of the spectrum. Instead, radio node 110-1 may need torepeat providing the grant request to computer 124, receiving the grantresponse from computer 124, providing a given instance of the keep-alivemessage and receiving a given instance of the keep-alive response beforetransmitting again in the granted portion of the spectrum. The resultingtime delays can degrade communication and quality of service in anetwork that includes radio node 110-1.

In order to prevent these problems, in the communication technique radionode 110-1 may dynamically adjust the transmit time based at least inpart on the receive time and the first instance of transmit expire time.Notably, radio node 110-1 may dynamically adjust or temporally offsetthe transmit time of a subsequent instance of the keep-alive messagebased at least in part on a difference between the first instance oftransmit expire time and the receive time. For example, when thedifference is less than 1, 2 or 5 s, the transmit time of the subsequentinstance of the keep-alive message may be temporally offset or reduced(e.g., to before or prior to a start of the time interval, such as by 5,10 or 30 s) during a time window corresponding to a subsequent instanceof the transmit expire time, so that there is more time forcommunication (including any retries) and processing of a given instanceof the keep-alive message. In some embodiments, the transmit time may bedynamically adjusted or temporally offset based at least in part on: thetransmit time (which may provide compensation for the time needed forany retries); a number of instances of the keep-alive message that wereprovided until the keep-alive response was received (which may providecompensation for the time needed for any retries); and/or an previousoccurrence in which no instance of the keep-alive response is receivedprior to a previous instance of the transmit expire time (which mayindicate that the current transmit time does not provide sufficientmargin to avoid loss of authorization to transmit in the granted portionof the spectrum).

The aforementioned operations in the communication technique may berepeated so that radio node 110-1 can dynamically adapt to changes incommunication environment 108. For example, the communication techniquemay be performed once (such as when radio node 110-1 is turned on),periodically (such as, e.g., every 50 ms), as needed (such as when thereare delays in receiving a given instance of the keep-alive response)and/or continuously.

In this way, the communication technique may selectively and dynamicallyensure that there is sufficient time for radio node 110-1 to receive asubsequent instance of the keep-alive response. This may ensure thatradio node 110-1 remains authorized to transmit in the granted portionof the spectrum. Consequently, the communication technique may reduce oreliminate delays and may improve communication performance.

In general, the wireless communication in FIG. 1 may be characterized bya variety of performance metrics, such as: a data rate for successfulcommunication (which is sometimes referred to as ‘throughput’), an errorrate (such as a retry or resend rate), a mean-square error of equalizedsignals relative to an equalization target, intersymbol interference,multipath interference, a signal-to-noise ratio, a width of an eyepattern, a ratio of number of bytes successfully communicated during atime interval (such as 1-10 s) to an estimated maximum number of bytesthat can be communicated in the time interval (the latter of which issometimes referred to as the ‘capacity’ of a communication channel orlink), and/or a ratio of an actual data rate to an estimated data rate(which is sometimes referred to as ‘utilization’).

During the communication in FIG. 1, radio nodes 110 and electronicdevice 112 may wirelessly communicate while: transmitting accessrequests and receiving access responses on wireless channels, detectingone another by scanning wireless channels, establishing connections (forexample, by transmitting connection requests and receiving connectionresponses), and/or transmitting and receiving frames that includepackets (which may include information as payloads).

As described further below with reference to FIG. 5, radio nodes 110 andelectronic device 112 may include subsystems, such as a networkingsubsystem, a memory subsystem and a processor subsystem. In addition,radio nodes 110 and electronic device 112 may include radios 118 in thenetworking subsystems. More generally, radio nodes 110 and electronicdevice 112 can include (or can be included within) any electronicdevices with the networking subsystems that enable radio nodes 110 andelectronic device 112 to wirelessly communicate with each other. Thiswireless communication can comprise transmitting access on wirelesschannels to enable electronic devices to make initial contact with ordetect each other, followed by exchanging subsequent data/managementframes (such as connection requests and responses) to establish aconnection, configure security options, transmit and receive frames orpackets via the connection, etc.

Moreover, as can be seen in FIG. 1, wireless signals 120 (represented bya jagged line) are transmitted by radios 118 in radio nodes 110 andelectronic device 112. For example, radio 118-1 in radio node 110-1 maytransmit information (such as frames or packets) using wireless signals120. These wireless signals are received by radios 118 in one or moreother electronic devices (such as radio 118-2 in electronic device 112).This may allow radio node 110-1 to communicate information to otherradio nodes 110 and/or electronic device 112. Note that wireless signals120 may convey LTE frames or packets.

In the described embodiments, processing a frame that includes packetsin radio nodes 110 and electronic device 112 may include: receiving thewireless signals with the frame; decoding/extracting the frame from thereceived wireless signals to acquire the frame; and processing the frameto determine information contained in the payload of the frame (such asthe packet).

Although we describe the network environment shown in FIG. 1 as anexample, in alternative embodiments, different numbers or types ofelectronic devices may be present. For example, some embodimentscomprise more or fewer electronic devices. As another example, inanother embodiment, different electronic devices are transmitting and/orreceiving frames that include packets.

We now describe embodiments of the method. FIG. 2 presents a flowdiagram illustrating an example of a method 200 for dynamicallyadjusting a transmit time of an instance of a keep-alive message, whichmay be performed by a radio node (such as one of radio nodes 110 in FIG.1). During operation, an interface circuit in the radio node mayprovide, at a transmit time during a first time interval correspondingto a first instance of a transmit expire time, a first instance of akeep-alive message (operation 210) to a computer, where a given instanceof the keep-alive message requests authorization to transmit in agranted portion of a spectrum.

Then, the interface circuit may receive, at a receive time prior to thefirst instance of a transmit expire time, an instance of a keep-aliveresponse (operation 212) associated with the computer, where theinstance of the keep-alive response authorizes the radio node totransmit in the granted portion of the spectrum until a second instanceof the transmit expire time has elapsed.

Moreover, the interface circuit may determine, based at least in part onthe receive time and the first instance of the transmit expire time, anupdated transmit time (operation 214), where the updated transmit timeis temporally offset relative to a transmit time during a second timewindow corresponding to the second instance of the transmit expire time.For example, the updated transmit time may be determined based at leastin part on a difference between the transmit expire time and the receivetime. Note that the updated transmit time may precede a start of thesecond time interval.

Next, the interface circuit may provide, at the updated transmit time,which is prior to the second instance of the transmit expire time, asecond instance of the keep-alive message (operation 216) addressed tothe computer.

Note that the computer may include a SAS. Moreover, the spectrum may beincluded in the CBRS. For example, the given instance of the keep-alivemessage may include a heartbeat request, the keep-alive response mayinclude a heartbeat response, and a given time interval may include aheartbeat interval.

Furthermore, the updated transmit time may be determined based at leastin part on the transmit time. In some embodiments, the updated transmittime may be determined based at least in part on a number of instancesof the keep-alive message that were provided until the keep-aliveresponse was received. Alternatively or additionally, the updatedtransmit time may be determined based at least in part on a previousoccurrence in which no instance of the keep-alive response is receivedprior to a previous instance of the transmit expire time. Note that theupdated transmit time may be determined based at least in part onoccurrence of a timeout (such as 10 s) following transmission of a giveninstance of the keep-alive message, which indicates that a givenkeep-alive response was not received in time in response to the givenkeep-alive message.

In some embodiments of method 200, there may be additional or feweroperations. Furthermore, the order of the operations may be changed,and/or two or more operations may be combined into a single operation.

Embodiments of the communication technique are further illustrated inFIG. 3, which presents a drawing illustrating an example ofcommunication among radio node 110-1 and computer 124. In FIG. 3, aninterface circuit (IC) 312 in radio node 110-1 may provide, at atransmit time during a time interval, a keep-alive message (KAM) 314 tocomputer 124. In response, computer 124 may provide a keep-aliveresponse (KAR) 316 to radio node 110-1.

Interface circuit 312 may receive, at a receive time prior to a currenttransmit expire time, keep-alive response 316. Then, interface circuit312 may determine 318, based at least in part on the receive time andthe current instance of the transmit expire time, an updated transmittime. Note that updated transmit time may be temporally offset from orsooner than the transmit time during a time window corresponding to asubsequent transmit expire time.

Subsequently, interface circuit 312 may provide, at updated transmittime, which is prior to a subsequent instance of the transmit expiretime, keep-alive message 320 to computer 124.

While FIG. 3 illustrates communication between components usingunidirectional or bidirectional communication with lines having singlearrows or double arrows, in general the communication in a givenoperation in this figure may involve unidirectional or bidirectionalcommunication.

In some embodiments of the communication technique, heartbeat messagesare used to ensure that a radio node can continue to transmit in agranted portion of a spectrum. Notably, a CBSD may transmit a heartbeatrequest to a SAS during a heartbeat interval preceding a transmit expiretime. For example, the heartbeat request may be transmitted at a startof the heartbeat time. If a heartbeat response is received at the CBSDfrom the SAS prior to the transmit expire time, then the CBSD maycontinue transmitting using the granted portion of the spectrum. Thus,two parameters typically specify the timing of the heartbeat messages,the transmit expire time (which is typically 4 min. or 240 s from thetime that the heartbeat response was received from the SAS) and theheartbeat interval (which is typically 40 s prior to the transmit expiretime, and is usually included in the grant response by the SAS).

In the communication technique, the transmit time of instances of theheartbeat request are dynamically updated in order to ensure sufficienttime margin and, thus, the receipt of instances of heartbeat responsesbefore the instances of the transmit expire time. This is illustrated inFIG. 4, which presents a drawing illustrating an example of a techniquefor dynamically adjusting a transmit time of a heartbeat request from aCBSD to a SAS. Notably, the CBSD may provide to the SAS a heartbeatrequest 414-1 at transmit time 416 during heartbeat interval 418-1. Inresponse, the SAS may provide a heartbeat response 420-1 to the CBSD attransmit time 408. When the CBSD receives heartbeat response 420-1 at areceive time 422 prior to transmit expire time 424-1, the use of agranted portion (with some or all) of a spectrum may be authorized untila subsequent transmit expire time 424-2 has elapsed or expired. Notethat receive time 422 may define the start of the subsequent transmitexpire time 424-2.

In the communication technique, when a time difference 426 betweentransmit expire time 424-1 and receive time 422 is less than apredefined amount (such as 1, 2, 5, or 10 s), the CBSD may update atransmit time 428 of a subsequent heartbeat request 414-2. For example,transmit time 428 may be temporally offset to an earlier time (and,thus, further from an end of transmit expire time 424-2). For example,heartbeat request 414-2 may be transmitted prior to or before heartbeatinterval 418-2. This may help ensure that the SAS may provide aheartbeat response 420-2 to the CBSD, which may be received at a receivetime 430 prior to transmit expire time 424-2.

By automatically backing off or using a preemptive heartbeat request,the communication technique may help ensure that the CBSD remainsauthorized to transmit in the granted portion of the spectrum.

In some embodiments, instead of sending a preemptive heartbeat requestbased at least in part on feedback (such as time difference 426), theCBSD may always send heartbeat requests 414 early (such as prior toheartbeat intervals 418). However, this approach may be inefficient andmay lead to increased overhead in the communication between the CBDS andthe SAS.

We now describe embodiments of an electronic device, which may performat least some of the operations in the communication technique. FIG. 5presents a block diagram illustrating an example of an electronic device500 in accordance with some embodiments, such as one of radio nodes 110,electronic device 112 computer 124. This electronic device includesprocessing subsystem 510, memory subsystem 512, and networking subsystem514. Processing subsystem 510 includes one or more devices configured toperform computational operations. For example, processing subsystem 510can include one or more microprocessors, graphics processing units(GPUs), ASICs, microcontrollers, programmable-logic devices, and/or oneor more digital signal processors (DSPs).

Memory subsystem 512 includes one or more devices for storing dataand/or instructions for processing subsystem 510 and networkingsubsystem 514. For example, memory subsystem 512 can include dynamicrandom access memory (DRAM), static random access memory (SRAM), and/orother types of memory. In some embodiments, instructions for processingsubsystem 510 in memory subsystem 512 include: one or more programmodules or sets of instructions (such as program module 522 or operatingsystem 524), which may be executed by processing subsystem 510. Notethat the one or more computer programs or program modules may constitutea computer-program mechanism. Moreover, instructions in the variousmodules in memory subsystem 512 may be implemented in: a high-levelprocedural language, an object-oriented programming language, and/or inan assembly or machine language. Furthermore, the programming languagemay be compiled or interpreted, e.g., configurable or configured (whichmay be used interchangeably in this discussion), to be executed byprocessing subsystem 510.

In addition, memory subsystem 512 can include mechanisms for controllingaccess to the memory. In some embodiments, memory subsystem 512 includesa memory hierarchy that comprises one or more caches coupled to a memoryin electronic device 500. In some of these embodiments, one or more ofthe caches is located in processing subsystem 510.

In some embodiments, memory subsystem 512 is coupled to one or morehigh-capacity mass-storage devices (not shown). For example, memorysubsystem 512 can be coupled to a magnetic or optical drive, asolid-state drive, or another type of mass-storage device. In theseembodiments, memory subsystem 512 can be used by electronic device 500as fast-access storage for often-used data, while the mass-storagedevice is used to store less frequently used data.

Networking subsystem 514 includes one or more devices configured tocouple to and communicate on a wired and/or wireless network (i.e., toperform network operations), including: control logic 516, an interfacecircuit 518 and one or more antennas 520 (or antenna elements). (WhileFIG. 5 includes one or more antennas 520, in some embodiments electronicdevice 500 includes one or more nodes, such as antenna nodes 508, e.g.,a pad, which can be coupled to the one or more antennas 520, or nodes506, which can be coupled to a wired or optical connection or link.Thus, electronic device 500 may or may not include the one or moreantennas 520. Note that the one or more nodes 506 and/or antenna nodes508 may constitute input(s) to and/or output(s) from electronic device500.) For example, networking subsystem 514 can include a Bluetooth™networking system, a cellular networking system (e.g., a 3G/4G/5Gnetwork such as UMTS, LTE, etc.), a universal serial bus (USB)networking system, a networking system based on the standards describedin IEEE 802.11 (e.g., a Wi-Fi® networking system), an Ethernetnetworking system, and/or another networking system.

Note that a transmit or receive antenna pattern (or antenna radiationpattern) of electronic device 500 may be adapted or changed usingpattern shapers (such as reflectors) in one or more antennas 520 (orantenna elements), which can be independently and selectivelyelectrically coupled to ground to steer the transmit antenna pattern indifferent directions. Thus, if one or more antennas 520 include Nantenna pattern shapers, the one or more antennas may have 2^(N)different antenna pattern configurations. More generally, a givenantenna pattern may include amplitudes and/or phases of signals thatspecify a direction of the main or primary lobe of the given antennapattern, as well as so-called ‘exclusion regions’ or ‘exclusion zones’(which are sometimes referred to as ‘notches’ or ‘nulls’). Note that anexclusion zone of the given antenna pattern includes a low-intensityregion of the given antenna pattern. While the intensity is notnecessarily zero in the exclusion zone, it may be below a threshold,such as 3 dB or lower than the peak gain of the given antenna pattern.Thus, the given antenna pattern may include a local maximum (e.g., aprimary beam) that directs gain in the direction of electronic device500 that is of interest, and one or more local minima that reduce gainin the direction of other electronic devices that are not of interest.In this way, the given antenna pattern may be selected so thatcommunication that is undesirable (such as with the other electronicdevices) is avoided to reduce or eliminate adverse effects, such asinterference or crosstalk.

Networking subsystem 514 includes processors, controllers,radios/antennas, sockets/plugs, and/or other devices used for couplingto, communicating on, and handling data and events for each supportednetworking system. Note that mechanisms used for coupling to,communicating on, and handling data and events on the network for eachnetwork system are sometimes collectively referred to as a ‘networkinterface’ for the network system. Moreover, in some embodiments a‘network’ or a ‘connection’ between the electronic devices does not yetexist. Therefore, electronic device 500 may use the mechanisms innetworking subsystem 514 for performing simple wireless communicationbetween the electronic devices, e.g., transmitting advertising or beaconframes and/or scanning for advertising frames transmitted by otherelectronic devices as described previously.

Within electronic device 500, processing subsystem 510, memory subsystem512, and networking subsystem 514 are coupled together using bus 528.Bus 528 may include an electrical, optical, and/or electro-opticalconnection that the subsystems can use to communicate commands and dataamong one another. Although only one bus 528 is shown for clarity,different embodiments can include a different number or configuration ofelectrical, optical, and/or electro-optical connections among thesubsystems.

In some embodiments, electronic device 500 includes a display subsystem526 for displaying information on a display, which may include a displaydriver and the display, such as a liquid-crystal display, a multi-touchtouchscreen, etc.

Electronic device 500 can be (or can be included in) any electronicdevice with at least one network interface. For example, electronicdevice 500 can be (or can be included in): a desktop computer, a laptopcomputer, a subnotebook/netbook, a server, a tablet computer, asmartphone, a cellular telephone, a smartwatch, a consumer-electronicdevice, a portable computing device, an access point, a transceiver, arouter, a switch, communication equipment, an eNodeB, a controller, testequipment, and/or another electronic device.

Although specific components are used to describe electronic device 500,in alternative embodiments, different components and/or subsystems maybe present in electronic device 500. For example, electronic device 500may include one or more additional processing subsystems, memorysubsystems, networking subsystems, and/or display subsystems.Additionally, one or more of the subsystems may not be present inelectronic device 500. Moreover, in some embodiments, electronic device500 may include one or more additional subsystems that are not shown inFIG. 5. Also, although separate subsystems are shown in FIG. 5, in someembodiments some or all of a given subsystem or component can beintegrated into one or more of the other subsystems or component(s) inelectronic device 500. For example, in some embodiments program module522 is included in operating system 524 and/or control logic 516 isincluded in interface circuit 518.

Moreover, the circuits and components in electronic device 500 may beimplemented using any combination of analog and/or digital circuitry,including: bipolar, PMOS and/or NMOS gates or transistors. Furthermore,signals in these embodiments may include digital signals that haveapproximately discrete values and/or analog signals that have continuousvalues. Additionally, components and circuits may be single-ended ordifferential, and power supplies may be unipolar or bipolar.

An integrated circuit (which is sometimes referred to as a‘communication circuit’) may implement some or all of the functionalityof networking subsystem 514. The integrated circuit may include hardwareand/or software mechanisms that are used for transmitting wirelesssignals from electronic device 500 and receiving signals at electronicdevice 500 from other electronic devices. Aside from the mechanismsherein described, radios are generally known in the art and hence arenot described in detail. In general, networking subsystem 514 and/or theintegrated circuit can include any number of radios. Note that theradios in multiple-radio embodiments function in a similar way to thedescribed single-radio embodiments.

In some embodiments, networking subsystem 514 and/or the integratedcircuit include a configuration mechanism (such as one or more hardwareand/or software mechanisms) that configures the radio(s) to transmitand/or receive on a given communication channel (e.g., a given carrierfrequency). For example, in some embodiments, the configurationmechanism can be used to switch the radio from monitoring and/ortransmitting on a given communication channel to monitoring and/ortransmitting on a different communication channel. (Note that‘monitoring’ as used herein comprises receiving signals from otherelectronic devices and possibly performing one or more processingoperations on the received signals)

In some embodiments, an output of a process for designing the integratedcircuit, or a portion of the integrated circuit, which includes one ormore of the circuits described herein may be a computer-readable mediumsuch as, for example, a magnetic tape or an optical or magnetic disk.The computer-readable medium may be encoded with data structures orother information describing circuitry that may be physicallyinstantiated as the integrated circuit or the portion of the integratedcircuit. Although various formats may be used for such encoding, thesedata structures are commonly written in: Caltech Intermediate Format(CIF), Calma GDS II Stream Format (GDSII) or Electronic DesignInterchange Format (EDIF). Those of skill in the art of integratedcircuit design can develop such data structures from schematics of thetype detailed above and the corresponding descriptions and encode thedata structures on the computer-readable medium. Those of skill in theart of integrated circuit fabrication can use such encoded data tofabricate integrated circuits that include one or more of the circuitsdescribed herein.

While the preceding discussion used an Ethernet and an LTE communicationprotocol as an illustrative example, in other embodiments a wide varietyof communication protocols and, more generally, wireless communicationtechniques may be used. For example, instead of Ethernet, acommunication protocol that is compatible with the Internet Protocol isused. Thus, the communication technique may be used in a variety ofnetwork interfaces. Furthermore, while some of the operations in thepreceding embodiments were implemented in hardware or software, ingeneral the operations in the preceding embodiments can be implementedin a wide variety of configurations and architectures. Therefore, someor all of the operations in the preceding embodiments may be performedin hardware, in software or both. For example, at least some of theoperations in the communication technique may be implemented usingprogram module 522, operating system 524 (such as a driver for interfacecircuit 518) or in firmware in interface circuit 518. Thus, thecommunication technique may be implemented at runtime of program module522. Alternatively or additionally, at least some of the operations inthe communication technique may be implemented in a physical layer, suchas hardware in interface circuit 518.

While examples of numerical values are provided in the precedingdiscussion, in other embodiments different numerical values are used.Consequently, the numerical values provided are not intended to belimiting.

While the preceding embodiments illustrated the use of the communicationtechnique with CBRS (e.g., a frequency band near 3.5 GHz), in otherembodiments of the communication technique different wireless signalsand/or different frequency band(s) may be used. For example, thewireless signals may be communicated in one or more bands offrequencies, including: 900 MHz, 2.4 GHz, 5 GHz, 60 GHz, and/or a bandof frequencies used by LTE or another cellular-telephone communicationprotocol.

In the preceding description, we refer to ‘some embodiments.’ Note that‘some embodiments’ describes a subset of all of the possibleembodiments, but does not always specify the same subset of embodiments.

The foregoing description is intended to enable any person skilled inthe art to make and use the disclosure, and is provided in the contextof a particular application and its requirements. Moreover, theforegoing descriptions of embodiments of the present disclosure havebeen presented for purposes of illustration and description only. Theyare not intended to be exhaustive or to limit the present disclosure tothe forms disclosed. Accordingly, many modifications and variations willbe apparent to practitioners skilled in the art, and the generalprinciples defined herein may be applied to other embodiments andapplications without departing from the spirit and scope of the presentdisclosure. Additionally, the discussion of the preceding embodiments isnot intended to limit the present disclosure. Thus, the presentdisclosure is not intended to be limited to the embodiments shown, butis to be accorded the widest scope consistent with the principles andfeatures disclosed herein.

What is claimed is:
 1. A radio node, comprising: a node or connectorconfigured to communicatively couple to a network; an interface circuit,communicatively coupled to the node or connector, configured tocommunicate with a computer, wherein the interface circuit is configuredto: provide, at a first transmit time during a first time intervalcorresponding to a first instance of a transmit expire time, a firstinstance of a keep-alive message addressed to the computer, wherein agiven instance of the keep-alive message requests authorization totransmit in a granted portion of a spectrum; receive, at a receive timeprior to the first instance of a transmit expire time, an instance of akeep-alive response associated with the computer, wherein the instanceof the keep-alive response authorizes the radio node to transmit in thegranted portion of the spectrum until a second instance of the transmitexpire time has elapsed; determine, based at least in part on thereceive time and the first instance of the transmit expire time, anupdated transmit time, wherein the updated transmit time is temporallyoffset relative to a second transmit time during a second time windowcorresponding to the second instance of the transmit expire time; andprovide, at the updated transmit time, which is prior to the secondinstance of the transmit expire time, a second instance of thekeep-alive message addressed to the computer.
 2. The radio node of claim1, wherein the computer comprises a spectrum allocation server (SAS). 3.The radio node of claim 1, wherein the spectrum comprises a band offrequencies associated with a Citizens Broadband Radio Service (CBRS).4. The radio node of claim 1, wherein the updated transmit time isdetermined based at least in part on a difference between the transmitexpire time and the receive time.
 5. The radio node of claim 1, whereinthe updated transmit time is determined based at least in part on thefirst transmit time.
 6. The radio node of claim 1, wherein the updatedtransmit time is determined based at least in part on a number ofinstances of the keep-alive message that were provided until thekeep-alive response was received.
 7. The radio node of claim 1, whereinthe updated transmit time is determined based at least in part on aprevious occurrence in which no instance of the keep-alive response isreceived prior to a previous instance of the transmit expire time. 8.The radio node of claim 1, wherein the updated transmit time precedes astart of the second time interval.
 9. The radio node of claim 1, whereinthe given instance of the keep-alive message comprises a heartbeatrequest, the keep-alive response comprises a heartbeat response, and agiven time interval comprises a heartbeat interval.
 10. The radio nodeof claim 1, wherein communication with the computer comprises wiredcommunication.
 11. The radio node of claim 1, wherein the radio nodecomprises: an Evolved Node B (eNodeB), a Universal MobileTelecommunications System (UMTS) NodeB and radio network controller(RNC), or a New Radio (NR) gNB or gNodeB.
 12. A non-transitorycomputer-readable storage medium for use in conjunction with a radionode, the computer-readable storage medium storing program instructionsthat, when executed by the radio node, cause the radio node to performoperations comprising: providing, at a first transmit time during afirst time interval corresponding to a first instance of a transmitexpire time, a first instance of a keep-alive message addressed to acomputer, wherein a given instance of the keep-alive message requestsauthorization to transmit in a granted portion of a spectrum; receiving,at a receive time prior to the first instance of a transmit expire time,an instance of a keep-alive response associated with the computer,wherein the instance of the keep-alive response authorizes the radionode to transmit in the granted portion of the spectrum until a secondinstance of the transmit expire time has elapsed; determining, based atleast in part on the receive time and the first instance of the transmitexpire time, an updated transmit time, wherein the updated transmit timeis temporally offset relative to a second transmit time during a secondtime window corresponding to the second instance of the transmit expiretime; and providing, at the updated transmit time, which is prior to thesecond instance of the transmit expire time, a second instance of thekeep-alive message addressed to the computer.
 13. The non-transitorycomputer-readable storage medium of claim 12, wherein the computercomprises a spectrum allocation server (SAS) and the spectrum comprisesa band of frequencies associated with a Citizens Broadband Radio Service(CBRS).
 14. The non-transitory computer-readable storage medium of claim12, wherein the updated transmit time is determined based at least inpart on a difference between the transmit expire time and the receivetime.
 15. The non-transitory computer-readable storage medium of claim12, wherein the updated transmit time is determined based at least inpart on the first transmit time.
 16. The non-transitorycomputer-readable storage medium of claim 12, wherein the updatedtransmit time is determined based at least in part on a number ofinstances of the keep-alive message that were provided until thekeep-alive response was received.
 17. The non-transitorycomputer-readable storage medium of claim 12, wherein the updatedtransmit time is determined based at least in part on a previousoccurrence in which no instance of the keep-alive response is receivedprior to a previous instance of the transmit expire time.
 18. Thenon-transitory computer-readable storage medium of claim 12, wherein theupdated transmit time precedes a start of the second time interval. 19.A method for dynamically adjusting transmit times of instances ofkeep-alive messages to a computer, comprising: by a radio node:providing, at a first transmit time during a first time intervalcorresponding to a first instance of a transmit expire time, a firstinstance of a keep-alive message addressed to the computer, wherein agiven instance of the keep-alive message requests authorization totransmit in a granted portion of a spectrum; receiving, at a receivetime prior to the first instance of a transmit expire time, an instanceof a keep-alive response associated with the computer, wherein theinstance of the keep-alive response authorizes the radio node totransmit in the granted portion of the spectrum until a second instanceof the transmit expire time has elapsed; determining, based at least inpart on the receive time and the first instance of the transmit expiretime, an updated transmit time, wherein the updated transmit time istemporally offset relative to a second transmit time during a secondtime window corresponding to the second instance of the transmit expiretime; and providing, at the updated transmit time, which is prior to thesecond instance of the transmit expire time, a second instance of thekeep-alive message addressed to the computer.
 20. The method of claim19, wherein the computer comprises a spectrum allocation server (SAS)and the spectrum comprises a band of frequencies associated with aCitizens Broadband Radio Service (CBRS).